Proper and satisfactory operation of delta/star transformers occurs under conditions where______________?
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Answer: C. on balanced as well as unbalanced loads
Explanation
Delta/star connected transformers feature a neutral connection on the secondary star side that provides a return path for current. Unbalanced phase loads generate zero-sequence current components that flow freely through the star secondary neutral conductor. The primary delta winding accommodates these unbalanced load currents by circulating compensating currents internally without core saturation. Delta/star transformer configurations step down medium transmission voltages to lower distribution levels for commercial customers. Balanced loads draw equal currents across all three phases, whereas unbalanced loads draw varying currents per phase. Zero-sequence currents are equal in magnitude and in phase with each other, requiring a neutral return path to prevent voltage distortion.
Restricting operation to balanced loads only is incorrect because the star neutral connection handles unbalanced loads effectively. Restricting operation to unbalanced loads only is false since the transformer handles perfectly balanced loads with equal efficiency. Stating none of the above is incorrect because delta/star transformers operate successfully under balanced and unbalanced conditions.
- Subject
- Engineering
- Category
- Electrical Engineering
- Topic
- —
- Difficulty
- medium
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